Specifications

Link Aggregation Overview
December 02, 2010 Page 4 of 23
Figure 1displaysaLAGformationexamplecontainingthreedeviceswithfive100Mbpsportsand
three1Gbportsconfigured.Forthisexample,allportsareoperatinginfull‐duplexmode,andthe
adminkeyforallLAGportshasbeensetto100.DeviceAistheactorandthereforedetermines
which
portswilljoinaLAG.DevicesBandCarethepartners.
InourexampletwoLAGshaveformedbecausetheactorportsaresharedbetweentwopartner
devices.AttemptingtoformasingleLAGusingalltheactorportswouldhavebrokentherule
thatactorandpartnerports
mustoperateinparallel.
Figure 1 LAG Formation
Actorports1‐3ondeviceAdirectlyconnecttopartnerports1‐3ondeviceB:
•Wehavealreadystatedthatallportsareoperatinginfull‐duplexmode,sorule1issatisfied
forallthreeports.
• Investigatingtheportadminkeys,weseethat
ports1and2ondeviceAaresetto100(the
samesettingasallLAGportsonthedevice),whileport3ondeviceAissetto200.Becausethe
portadminkeysarethesameforboththeLAGportandthesephysicalports,ports1
and2
satisfyrule2.Becausetheadminkeyforphysicalport3isdifferentfromanypossibleLAGfor
thisdevice,port3cannotbepartofanyLAG.
PARTNER
Port
Speed
Device
B
Device
A
Device
C
LAG 1
LAG 2
Admin
Key
ACTOR
Port
Speed
Admin
Key
100
100
100
100
100
100
100
100
100
100
100
100M
100M
100M
100M
100M
1Gb
1Gb
1Gb
100
100
200
100
100
100
300
400
100M
100M
100M
100M
100M
1Gb
1Gb
1Gb
100M
100M
100M
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
1
2
3